Rockwell Automation Publication 2080-UM002N-EN-E - November 2022
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Appendix
E
PID Function Blocks
The PID function block has parameter naming similar to RSLogix 500 and is recommended for
users who are already familiar with programming in RSLogix 500. The IPIDCONTROLLER
function block has the advantage of supporting auto tune.
Table 82 - Comparison Between IPIDCONTROLLER and PID
IPIDCONTROLLER
PID
Description
Common parameters
Process
PV
Process Variable feedback
Setpoint
SP
Set Point input
Output
CV
CV output
Gains.DirectActing
Control
Control direction of process (cooling versus heating).
Gains.ProportionalGain
Gains.Kc
Controller gain for both P and I
Gains.TimeIntegral
Gains.Ti
Time integral value for I
Gains.TimeDerivative
Gains.Td
Time derivative value for D
Gains.DerivativeGain
Gains.FC
A higher filter constant makes CV output more
responsive to error. Acts like a derivative gain.
AbsoluteError
AbsoluteError
Absolute value of error
PID-specific parameters
—
CVMin
For limiting CV
CVMax
For limiting CV
AutoManual
TRUE = Normal operation of PID.
FALSE = Manual operation using CVManual.
CVManual
CV when in manual mode
Enable
TRUE = Start execution with current input parameters.
FALSE = CV equals zero.
Active
TRUE = PID state is running.
FALSE = PID state is stopped.
Error
TRUE = PID has an error.
FALSE = PID has no errors.
ErrorID
PID Error ID
IPIDCONTROLLER-specific parameters
Auto
—
TRUE = Normal operation of PID.
FALSE = Output tracks Feedback.
Feedback
Feedback of the control being applied to the process.
Usually it’s the PID’s CV after any limits or manual
control has been applied.
AutoTune
TRUE = Autotune.
FALSE = No Autotune.
ATParameters
Autotune parameters
ATWarning
Autotune warning
OutGains
Gains from Autotune
Initialize
Used for AutoTune